Looking Up: Fiery red star of winter

One of the most striking stars in the entire night sky, visible to unaided eyes, has to be fiery red Betelgeuse.

Peter Becker

One of the most striking stars in the entire night sky, visible to unaided eyes, has to be fiery red Betelgeuse.

This beacon of the constellation Orion gives any stargazer pause to stop and admire, fitting for a star with a traffic light color.

Betelgeuse is prominently seen on winter evenings, the top left bright star in Orion, shining in the southern sky. It is also called Alpha Orionis but probably by very few, and only by squeamish folks who think “Betelgeuse” has something to do with beetles.

The star’s name is derived from Arabic.

The eighth brightest star in the night sky, Betelgeuse varies on an irregular cycle, from magnitude 0.3 to 1.2. The color is actually more red-orange, but describing the hue of any star is somewhat subjective. What do you think of the color? Is it more red like an apple, orange like an orange or floating between a peach and an apricot?

Curiously, Chinese astronomers from the first century B.C. described Betelgeuse as yellow (lemon?).

Betelgeuse is classified as a red supergiant star, a highly inflated and advanced stage in a star’s cycle of development. Betelgeuse is one of the largest and most luminous stars we know. If the sun were replaced with Betelgeuse, the great girth of this star would engulf the orbits of Mercury, Venus, Earth and Mars, and may extend as far as Jupiter.

The star is expected to explode as a supernova within the next million years. Astronomers have suspected that Betelgeuse is related to the many other stars in the direction of Orion, including the three “belt” stars, having risen from the same nebula.

The distance to Betelgeuse is currently thought to be approximately 640 light years, meaning the light from Betelgeuse you see tonight has been traveling through space since the year 1372. Another way to look at it: If there is currently an alien civilization on a planet circling Betelgeuse with a telescope powerful enough to detect Earth and surface details, the alien would be looking at the life and times of medieval Europe and the Chinese Ming Dynasty.

Because it so large and relatively near, the angular diameter has been observable in large telescopes. Measurements were first taken in 1920.

There are several other red or orange colored stars visible to the unaided eye or with binoculars, and many more with a small telescope. It can be great sport sweeping the heavens on a dark, clear night with a telescope, and stumbling across stars of various shades. Red, orange, yellow, bluish-white and white are most evident. Stars have to be sufficiently bright for our eyes to detect color, as the portion of our retinas that detect color do not respond well in darkness.

Another bright red-orange star in the winter evening sky is Aldebaran, located to the upper right of Orion. Higher up, to the left, is the brilliant yellow star Capella. On summer evenings, a well-known, bright red star is Antares, in the constellation Scorpius.

First-quarter moon is on Jan. 30.

Comments and questions are welcome any time at news@neagle.com.

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